Concluding Remarks

In the present chapter entirely new analyses, as compared to previous chapters, have been presented on instability in rotor systems. The main focus was to illustrate various kinds of instability and rotor phenomena with the help of simple rotor models. Instability due to fluid-film bearings, the internal damping in the rotor, the shaft asymmetry, steam whirl, and seal induced instability have been dealt. The Routh-Hurtwiz linear instability criterion was the main focus of the present chapter. Apart from these, the secondary critical speed due to gravity and the rotor dynamic behaviour with variable speeds (or the angular acceleration) have been dealt including the non-linearity in the rotor system especially in the torsional angular displacement. In subsequent chapter, instability of multi-DOFs rotor-bearing system with the help of finite element method will be described, which has direct practical application.